Meter and a method for measuring quantity of a flowing liquid

ABSTRACT

A meter for measuring the quantity of milk by weight flowing in a pipeline comprises a main housing having a main milk inlet pipe and a main milk outlet pipe. A buffer chamber in the main housing receives and holds the milk prior to weighing. A weighing container in a weighing chamber sequentially receives discrete quantities of milk from the buffer chamber through a communicating opening. The weighing container is mounted on a load cell, which sequentially weighs the settled weights of the discrete quantities of milk, the settled weights of which are cumulatively stored. Weighed milk is discharged from the weighing container through a discharge outlet opening. A main valve member and a secondary valve member selectively close the communicating opening and the discharge outlet, respectfully. Milk samples are collected in a milk sample reservoir on discharge of weighed discrete quantities of milk from the weighing container for subsequent collection in a collection jar.

The present invention relates to a meter and a method for measuring thequantity by weight of a flowing liquid, and in particular, for measuringthe quantity by weight of a liquid flowing through a pipeline.

In many instances it is desirable to measure a quantity of liquidflowing through a pipeline. For example, it is desirable to measure thequantity of milk flowing through a milk pipeline between a cluster ofmilking teats and a milk holding vacuum jar so that a farmer can monitorthe milk output of each cow. In intensive milk production farms, it isessential for a farmer to know the milk output of each animal. Metersfor measuring the quantity of milk and other liquids flowing in apipeline are known. Typically, such meters measure the volume of liquidflowing in the pipeline. A typical type of such meter is an impellertype meter which comprises an impeller disposed in the liquid flow whichis rotatable by the flowing liquid. The number of rotations of theimpeller are counted for determining the quantity of the liquid flowingthrough the pipeline. Such impeller type meters are reasonably accuratefor determining the quantity of liquid flow in cases where the liquid isof uniform density throughout and does not tend to froth or foam.However, such meters are unsuitable for measuring the quantity of milkflowing in a pipeline. Milk flowing through a pipeline between thecluster of milking teats and the vacuum holding jar contains aconsiderable amount of entrained air, and furthermore, the quantity ofentrained air is not uniform. Additionally, the density of milk variesconsiderably during a milking cycle of a cow. Initially, at thebeginning of a milking cycle, the milk tends to comprise a relativelyhigh proportion of water, while towards the end of the milking cycle themilk tends to have a considerably higher proportion of fat. Furthermore,there is a considerable tendency for the milk to froth and foam, whichfurther leads to inaccuracies in measuring the quantity of milk flowingin the pipeline. Accordingly, such impeller type meters are unsuitablefor measuring the quantity of milk milked from a cow. An alternativeconstruction of meter comprises a container of known volume which isplaced in the path of the flowing milk. On the milk reaching apredetermined level in the container, the milk is discharged from thecontainer which is again filled. However, because of the quantity ofentrained air, froth, foaming of the milk and to a lesser extent thevariation in density of the milk, such meters likewise are inaccurateand unreliable.

British Patent Specification No. 2,113,856A discloses a meter formeasuring quantity of milk flowing in a pipeline by weight. In thismeter, milk is delivered into a compensating vessel and in turn into aweighing container. The weight of the milk in the container isdetermined during a period while milk is accumulating in the container.The container is then emptied at a rate much greater than the maximumsupply rate of milk into the weighing container so that the level ofmilk in the weighing container falls. The cycle repeats. Series ofweight values each representing one accumulation period are fed to acomputer which interpolates values for the intervening emptying periods.This meter, while it does determine the quantity of milk flowing in apipeline by weight, is likewise inaccurate in that it relies onestimates being made of the milk delivered into the weighing containerduring the emptying period.

There is therefore a need for a meter which measures the quantity byweight of a liquid flowing in a pipeline more accurately than prior artdevices. In certain cases, there is also the need for such a meter whichis suitable for taking a representative sample of all the liquid beingweighed. For example it is desirable that a representative sample ofmilk being milked from a cow should include samples of milk oversubstantially the entire milking cycle.

It is an object of the invention to provide a meter and a method formeasuring the quantity by weight of a flowing liquid, and in particulara liquid flowing in a pipeline. It is a particular object of theinvention to provide a meter and a method for measuring the quantity byweight of a flowing liquid where the liquid is susceptible to frothingand foaming and the liquid is of variable density. It is a secondaryobject of the invention to provide such a meter and method which alsoprovides for sampling of the liquid.

According to the invention, there is provided a meter for measuring thequantity by weight of a flowing liquid, the meter comprising a housingdefining a buffer chamber for receiving and holding the liquid to beweighed, a main inlet means being provided into the buffer chamber forthe liquid, weighing means for sequentially weighing discrete quantitiesof the liquid, first communicating means communicating the bufferchamber with the weighing means for delivering the liquid into theweighing means, main valve means co-operating with the firstcommunicating means for selectively closing the first communicatingmeans for isolating the weighing means from the buffer chamber aftereach discrete quantity of liquid has been delivered into the weighingmeans, a discharge outlet means from the weighing means for deliveringthe weighed discrete quantities of liquid from the weighing means, andsecondary valve means co-operating with the discharge outlet means forclosing the discharge outlet means and for selectively opening thedischarge outlet means after each discrete quantity of liquid in theweighing means has been weighed.

The advantages of the invention are many. By virtue of the fact that thequantity is determined by weight, and all liquid flowing is weighed indiscrete quantities, an accurate measurement of the quantity of liquidflowing is obtained. The measured quantity is unaffected by variation inthe consistency and/or the density of the liquid. The measured quantityis also unaffected by the inclusion of entrained air and the like in theliquid or by frothing or foaming. The provision of the buffer chamberaccommodates accumulation of liquid while each discrete quantity of theliquid is being weighed.

In one embodiment of the invention, the main valve means is responsiveto the weighing means for closing the first communicating means on theweighing means determining that the approximate weight of the liquid inthe weighing means is equal to a predetermined weight. This feature ofthe invention provides a particularly important advantage in that themeter with this feature is suitable for dealing efficiently with liquidsflowing over the full range of flow rates from zero flow rate up to themaximum capacity of the meter without the risk of liquid overflowingfrom, overloading or being lost from the weighing means. It will beappreciated that the maximum flow rate with which the meter can copewill depend essentially on the capacity of the weighing means and thecycle time required for weighing each discrete quantity of liquid. Byvirtue of the fact that the main valve means is responsive to theweighing means, the main valve means closes on the weighing meansdetermining that the weight of the discrete quantity of liquid in theweighing means is substantially equal to the predetermined weight. This,thus, avoids any danger or risk of a greater quantity of liquid thanthat with which the weighing means can cope being delivered to theweighing means. Additionally, in the event of relatively low flow rates,the main valve means remains open until the discrete quantity of liquidin the weighing means is substantially equal to the predeterminedweight.

In another embodiment of the invention, the secondary valve means isresponsive to the weighing means for opening the discharge outlet meanson the weighing means having determined a substantially steady stateweight of each discrete quantity of liquid in the weighing means.

The advantage of this feature of the invention is that the measuredweight of each discrete quantity of liquid is particularly accurate.

In another embodiment of the invention, the main valve means isresponsive to the secondary valve means for opening the firstcommunicating means on the secondary valve means having closed thedischarge outlet means.

The advantage of this feature of the invention is that it ensures thatall liquid flowing through the meter is weighed.

Advantageously, the apparatus comprises a timing means. Preferably, thesecondary valve means is responsive to the timing means for closing thedischarge outlet means on the timing means having timed a predetermineddischarge time period after the secondary valve means has opened thedischarge outlet means.

The advantage of this feature of the invention is that it ensures thatdouble weighing of the liquid passing through the meter does not occur.

In a further embodiment of the invention, the main valve means isresponsive to the timing means for opening the first communicating meanson the timing means having timed a predetermined delay time period afterthe secondary valve means has closed the discharge outlet means.

The advantage of this feature of the invention is that it provides forrelatively accurate measuring of the liquid.

In one embodiment of the invention, the weighing means is responsive tothe timing means for determining the steady state weight of eachdiscrete quantity of liquid in the weighing means on the timing meanshaving timed a predetermined settling time period after the weighingmeans has determined the approximate weight of liquid in the weighingmeans being equal to the predetermined weight. The advantage of thisfeature of the invention is that it provides a relatively accuratemeter.

Preferably, the housing defines a weighing chamber, the weighing chambercommunicating with the buffer chamber through the first communicatingmeans, the weighing means being mounted in the weighing chamber, and amain outlet means being provided from the weighing chamber fordelivering weighed liquid therefrom, the main outlet means communicatingwith the discharge outlet means.

The advantage of this feature of the invention is that it facilitatesconnecting the meter to a pipeline.

In one embodiment of the invention, the weighing means comprises aweighing container defining a hollow interior region for receiving theliquid through an open mouth, and for holding the liquid duringweighing, the weighing container being mounted on the housing by a loadcell for weighing the liquid.

The advantage of this feature of the invention is that it provides aconvenient construction of meter and also provides a relatively accuratemeter.

Preferably, the load cell comprises a shear beam load cell.

The advantage of providing a shear beam load cell is that it facilitatesaccurate weighing of the discrete quantities of the liquid, andfurthermore, in general, the weights recorded by the load cell areunaffected by the distance of the centre of gravity of the weighingcontainer and liquid combined from the load cell.

Preferably, the load cell is mounted horizontally, and a substantiallyhorizontal carrier shaft extends centrally from the load cell forcarrying the weighing container.

The advantage of this feature of the invention is that it provides aconvenient construction and accurate meter.

Preferably, the carrier shaft extends from a side wall of the weighingcontainer. Advantageously, the load cell is mounted externally of thehousing, the carrier shaft extending through the housing and beingsealably engaged therein.

In another embodiment of the invention, the buffer chamber is providedabove the weighing means for accommodating liquid flow through the firstcommunicating means under gravity.

The advantage of this feature of the invention is that it provides for aconvenient and effective construction of meter.

In a preferred embodiment of the invention, the main valve meanscomprises a main valving member co-operating with the firstcommunicating means and being movable between an open position with thebuffer chamber and weighing means communicating and a closed positionisolating the buffer chamber from the weighing means. Preferably, a mainactuating means is provided for moving the main valving member betweenthe closed position and the open position. Advantageously, the mainactuating means comprises a vacuum operated main diaphragm actuator, themain diaphragm actuator being arranged for urging the main valvingmember into the open position under vacuum. Preferably, main biasingmeans is provided for urging the main valving member into the closedposition.

The advantage of these features of the invention is that it provides fora relatively convenient and robust construction of meter, and alsoprovides for a relatively accurate meter.

In another embodiment of the invention, the secondary valve meanscomprises a secondary valving member co-operating with the dischargeoutlet means, the secondary valving member being movable between an openposition with the discharge outlet means open to a closed position withthe discharge outlet means closed. Preferably, a secondary actuatingmeans is provided for moving the secondary valving member between theopen and closed positions, and an operating member operably connects thesecondary actuating means with the secondary valving member, theoperating member being disengagable with the secondary valving member onthe secondary valving member being in the closed position.Advantageously, the secondary actuating means comprises a vacuumoperated secondary diaphragm actuator, the vacuum operated secondarydiaphragm actuator being arranged for operating the secondary valvingmember into the closed position on a vacuum being applied. In oneembodiment of the invention, first secondary biasing means is providedfor urging the secondary valving member into the closed position.Advantageously, second secondary biasing means is provided for urgingthe secondary valving member into the open position.

The advantage of these features of the invention is that it provides fora relatively convenient and robust construction of meter, which is alsorelatively accurate.

In one embodiment of the invention, a baffle means is provided in thefirst communicating means for minimizing the effect of the liquidflowing into the weighing means on the weighing means.

In another embodiment of the invention, a control means is provided forcontrolling the operation of the meter, the control means comprisingmonitoring means for reading the output of the weighing means, weightstoring means for cumulatively storing the steady state weights of thediscrete quantities of liquid read by the monitoring means.

In one embodiment of the invention., the control means comprises thetiming means, and activating means for activating the operation of themain and secondary valve means. Preferably, the activating meanscomprises respective main and secondary solenoid valves for applying avacuum to the respective main and secondary actuating means.

In another embodiment of the invention, second communicating means isprovided for communicating the buffer chamber with the weighing meansfor maintaining the buffer chamber and weighing means at substantiallythe same pressure, the second communicating means being located to avoidflow of liquid through the second communicating means from the bufferchamber to the weighing means during normal operation of the meter.Preferably, second communicating means communicates the buffer chamberand the weighing chamber.

Preferably, sampling means is provided for collecting a liquid sampleeach time a weighed discrete quantity of liquid is discharged from theweighing means, and a liquid sample storing means is provided forstoring the liquid samples. Advantageously, agitating means is providedfor agitating the liquid samples in the liquid sample storing means.Preferably, the agitating means is operable on movement of the secondaryvalve means. In one embodiment of the invention, overflow means isprovided from the liquid sample storing means, the overflow meanscommunicating with the main outlet means.

In a further embodiment of the invention, a secondary outlet means isprovided from the liquid sample storing means, and receiving means forreleasably receiving a collecting vessel for collecting a liquid sampleis provided, an outlet valve means selectively communicating thereceiving means with the secondary outlet means for delivering liquidsamples from the liquid sample storing means to the collecting vessel,and the outlet valve means selectively communicating the main outletmeans with the secondary outlet means.

Preferably, the outlet valve means is a three position valve meanshaving a first position in which the receiving means is connected to thesecondary outlet means and the main outlet means for applying a vacuumon the receiving means for drawing milk samples from the milk samplereservoir into the collecting vessel mounted on the receiving means, asecond position in which the secondary outlet means is connected to themain outlet means for drawing milk samples into the main outlet means,and a third position in which the secondary outlet means and the mainoutlet means are respectively closed and isolated from the receivingmeans and from each other.

In one embodiment of the invention, the sampling means and liquid samplestoring means are provided in the weighing chamber.

In a further embodiment of the invention, the meter is adapted forconnecting into a pipeline in which the liquid is flowing so that allthe liquid flowing in the pipeline flows through the meter, the maininlet means being adapted for connecting to an upstream portion of thepipeline, and the main outlet means being adapted for connecting into adownstream portion of the pipeline. Preferably, the main housing isairtight for maintaining a vacuum applied to the pipeline and formaintaining the said vacuum in the housing. In one embodiment of theinvention, the meter is suitable for measuring the quantity of milk byweight flowing in a pipeline.

Preferably, the meter is suitable for connecting into a milk pipelinedelivering milk from a milking cluster to a milk holding vacuum jar.

Additionally, the invention provides a method for measuring the quantityby weight of a flowing liquid, the method comprising the steps offeeding the liquid into a buffer chamber, sequentially deliveringdiscrete quantities of the liquid from the buffer chamber into aweighing means, isolating the weighing means from the buffer chamberafter each discrete quantity of liquid has been delivered into theweighing means, sequentially determining the weight of the discretequantities of liquid in the weighing means, and discharging the weigheddiscrete quantities of liquid from the weighing means. Preferably, theweighing means is isolated from the buffer chamber on the weighing meanshaving determined that the approximate weight of liquid in the weighingmeans is equal to a predetermined weight.

Advantageously, the weighing means determines a substantially steadystate weight of each discrete quantity of liquid.

The advantages provided by the method according to the invention aresubstantially similar to the advantages provided by the meter accordingto the invention.

In one embodiment of the invention, the method further comprises thestep of taking a sample of each weighed discrete quantity of liquid asthe discrete quantities of liquid are being discharged from the weighingmeans.

Preferably, the samples are stored and agitated for subsequentcollection. In one embodiment of the invention, the weighed liquid isdischarged from the weighing means through a discharge outlet means.Preferably, the discharge outlet means is closed after a predetermineddischarge time period has elapsed from the time the discharge outletmeans is open for discharging each weighed discrete quantity of liquidfrom the weighing means. Advantageously, the buffer chamber communicateswith the weighing means through a first communicating means and a mainvalve means is provided in the first communicating means for selectivelyclosing the first communicating means for isolating the buffer chamberfrom the weighing means and the method includes the step of timing apredetermined delay time period after the discharge outlet means hasbeen closed before the first communicating means is open.

The invention will be more clearly understood from the followingdescription of a preferred embodiment thereof given by way of exampleonly with reference to the accompanying drawings, in which:

FIG. 1 is a perspective view of a meter according to the invention formeasuring the quantity by weight of a flowing liquid,

FIG. 2 is a perspective view of the meter of FIG. 1 with portion of themeter removed,

FIG. 3 is a cross sectional elevational view of the meter of FIG. 1,

FIG. 4 is a cross sectional elevational view of the meter of FIG. 1 onthe line IV--IV of FIG. 3,

FIG. 5 is a plan view of portion of the meter of FIG. 1,

FIG. 6 is another plan view of the portion of FIG. 5 showing part of theportion in section,

FIG. 7 is an exploded perspective view of another portion of the meterof FIG. 1,

FIG. 8 is an elevational view of part of the portion of FIG. 7,

FIG. 9 is an underneath perspective view of another portion of the meterof FIG. 1,

FIG. 10 is a cut-away perspective view of a detail of the meter of FIG.1,

FIG. 11 is a perspective view of another portion of the meter of FIG. 1,

FIG. 12 is a sectional elevational view of the portion of the meter ofFIG. 11,

FIG. 13 is a view similar to FIG. 12 of the portion in a differentposition,

FIG. 14 is a view similar to FIG. 12 of the portion in a still furtherdifferent position,

FIG. 15 is a block representation of a circuit diagram of the meter ofFIG. 1, and

FIG. 16 is a timing diagram showing the operation of parts of the meterof FIG. 1.

Referring to the drawings, there is illustrated a meter 1 according tothe invention indicated generally by the reference numeral 1 formeasuring quantity by weight of a liquid flowing in a pipeline. Themeter 1 is particularly suitable for measuring quantity of milk byweight flowing in a pipeline 2 which extends between a cluster ofmilking teats and a vacuum milk holding jar, neither of which are shown,for determining the quantity by weight of milk milked from a cow. Onlyportion of the pipeline 2 is illustrated, namely, an upstream portion 3which communicates with the cluster of milking teats, and a downstreamportion 4 which communicates with the vacuum milk holding jar. The meter1 comprises a main housing 7 of injection moulded transparent plasticsmaterial. The main housing 7 comprises two parts, namely, a lowerhousing 8 and an upper housing 9 of substantially cylindricalconstruction which are axially aligned with each other one above theother. The lower housing 8 comprises an elongated lower cylindrical sidewall 10 open at one end 11 and closed at the other end 12 by a base 14integrally formed with the side wall 10. The lower side wall 10 and base14 form a weighing chamber 15 where the milk is weighed as will bedescribed below.

The upper housing 9 comprises an elongated upper cylindrical side wall18 which is open at one end 19 and closed at the other end 20 by a base22 integrally formed with the upper side wall 18. An end cap 25 ofinjection moulded plastics material closes the open end 19 of the upperhousing 9 and forms with the upper side wall 18 and base 22 a bufferchamber 24 for receiving and holding milk to be weighed. The base 22 ofthe upper housing 9 closes the open end 11 of the lower housing 8 toform with the lower side wall 10 and base 14 the weighing chamber 15.

An annular groove 26 extending around the lower side wall 10 adjacentthe open end 11 carries an O-ring seal 27 for sealably engaging the base22 of the upper housing 9 to maintain an airtight seal. A groove 28 inthe end cap 25 carries an O-ring seal 29 for sealably engaging the upperside wall 18 for forming an airtight seal between the end cap 25 and theupper housing 9.

The lower housing 8, the upper housing 9 and the end cap 25 are retainedtogether in sealable engagement by three pairs of clips 30 of resilientstainless steel. The pairs of clips 30 are pivotally mounted on mountingmembers 31 integrally moulded with the upper housing 9 and disposed atintervals of 120° around the upper side wall 18. Pivot pins 32 carry theclips 30 which engage corresponding receivers 33 and 34 which areintegrally moulded with the lower housing 8 and end cap 25,respectively. The receivers 33 and 34 are disposed at intervals of 120°around the lower housing 8 and end cap 25, respectively.

A main inlet means, namely, a main inlet pipe 35 extends from the endcap 25 for communicating the upstream portion 3 of the pipeline 2 withthe buffer chamber 24. A main outlet means, namely, a main outlet pipe36 extends from the base 14 of the lower housing 8 for deliveringweighed milk from the weighing chamber 15 into the downstream portion 4of the pipeline 2.

First communicating means formed by a communicating opening 39 in thebase 22 of the upper housing 9 communicates the weighing chamber 15 withthe buffer chamber 24 so that milk in the buffer chamber 24 flows undergravity into the weighing chamber 15. A main valve means, namely, a mainvalving member 40 selectively closes the communicating opening 39 forisolating the weighing chamber 15 from the buffer chamber 24 duringweighing of the milk as will be described below. The main valving memberis carried on a main spindle 41 and is operated by an actuating means,namely, a vacuum operated main diaphragm actuator 42 mounted in the endcap 25 as will be described below.

Weighing means for sequentially weighing discrete quantities of milk ofpredetermined size comprises a weighing container 45 mounted in theweighing chamber 15 by a load cell 46 as will be described below. Theweighing container 45 is of injection moulded plastics material andcomprises a cylindrical side wall 47 extending upwardly from a base 48and terminating in an outwardly directed lip 51. The base 48 and theside wall 47 define a hollow interior region 43 for receiving thediscrete quantities of milk. The lip 51 forms an upwardly directed openmouth 44 for receiving milk from the communicating opening 39 into thehollow interior region 43 of the weighing container 45. A dischargeoutlet means is formed in the base 48 by a discharge outlet opening 49for discharging the weighed discrete quantities of milk from theweighing container 45 into the weighing chamber 15 and in turn throughthe main outlet pipe 36. A secondary valve means comprising a secondaryvalving member 50 closes the discharge outlet 49, and selectively opensthe discharge outlet 49 for discharging the weighed discrete quantitiesof milk after weighing. The secondary valving member 50 will bedescribed in more detail below.

A secondary housing 53 formed integrally with the lower housing 8 andextending sidewardly therefrom houses the load cell 46. In thisembodiment of the invention, the load cell 46 is a shear beam load celland is mounted in a carrier housing 54 of plastics material located inthe secondary housing 53. The carrier housing 54 engages a mountingopening 55 formed in the side wall 10 of the lower housing 8. Aresilient sealing member 56 extends around the carrier housing 54 in themounting opening 55 for sealably and resiliently securing the carrierhousing 54 in the side wall 10. Three screws 57 secure the load cell 46in the carrier housing 54. A carrier shaft 58 carried in a bore 59 inthe load cell 46 extends from the load cell 46 through the carrierhousing 54 to the weighing chamber 15 for carrying the weighingcontainer 45. A head 60 on the carrier shaft 58 is retained captive inthe side wall 47 of the weighing container 45 by virtue of it beinginsert moulded into the weighing container 45 during injection mouldingof the weighing container 45. The bore 59 is co-axially formed in theload cell 46 so that the carrier shaft 58 is in turn co-axial with theload cell 46. In this way, an accurate reading of the weight of thediscrete quantities of milk in the weighing container 45 is obtained. Ascrew 61 in the load cell 46 retains the carrier shaft 58 in the loadcell 46. A sealing arrangement which comprises a bellows seal 62 aroundthe carrier shaft 58 forms an airtight seal between the weighing chamber15 and the secondary housing 53. The bellows seal 62 tightly andsealably engages the carrier shaft 58 and is sealably engaged in acircular opening 63 through the carrier housing 54 which accommodatesthe carrier shaft 58. A retaining ring 64 having a fusto-conical outersurface 65 sealably secures the bellows seal 62 against acorrespondingly shaped surface 66 in the opening 63. Screws 52 retainthe retaining ring 64 in engagement with the bellows seal 62 in theopening 63. A stainless steel sleeve 67 extending along the carriershaft 58 between the weighing container 45 and the load cell 46 urgesthe bellows seal 62 into tight sealing engagement with the weighingcontainer 45 to further enhance the formation of an airtight sealbetween the weighing chamber 15 and the secondary housing 53. A bore 73,see FIGS. 3 and 10, through the retaining ring 64 accommodates thecarrier shaft 58 and the sleeve 67 through the retaining ring 64. Thebore 73 is of sufficiently large diameter to provide good clearancebetween the sleeve 67 and the retaining ring 64 to facilitate sufficientvertical movement of the carrier shaft 58 relative to the housing toenable the weighing container 45 and the contents therein to induce astrain in the load cell 46 for weighing of the weighing container 45. Alid 68 closes the carrier housing 54 and a sealing gasket 69 is disposedbetween the lid 68 and the carrier housing 54. Screws 70 secure the lid68 to the secondary housing 53 and a clip 71 similar to the clips 30which is pivotally connected to the secondary housing 53 and engagablewith a receiver 72 of the lid 68 further secures the lid 68 to thecarrier housing 54.

Strain gauges 74 mounted on the top and bottom faces of the load cell 46are connected by electrical cables 75 to a control means, namely, acontrol circuit 76 described below for monitoring of the load cell 46. Agrommet 77 accommodates the cables 75 through the carrier housing 54. Anopening 78 in the secondary housing 53 accommodates the cables 75 into alower compartment 79 of the secondary housing 53 within which thecontrol circuit 76 is housed.

By virtue of the fact that the load cell 46 is a shear beam load cell,provided the carrier shaft 58 is co-axial with the load cell 46, theweight recorded by the load cell 46 will be the accurate weight of eachdiscrete quantity of milk in the weighing container 45 allowing for theweight of the weighing container 45 irrespective of the distance of theweighing container 45 or the distance of the combined centre of gravityof the weighing container 45 and milk contained therein from the loadcell.

Turning now to the main valving member 40, the main valving member 40 isprovided with a peripheral valving face 82 which sealably engages avalve seat 83 extending around the periphery of the communicatingopening 39. The main spindle 41 is located in a bushing 85 in a bore 84extending through the end cap 25. The spindle 41 is axially slidable inthe bushing 85 for moving the valving member 40 between an open position(see FIG. 4) spaced apart from the valve seat 83 with the weighingchamber 15 and buffer chamber 24 communicating, and a closed position(see FIG. 3) with the valve face 82 sealably engaging the valve seat 83for isolating the weighing chamber 15 from the buffer chamber 24 aftereach discrete quantity of milk has been delivered into the weighingcontainer 45. The main diaphragm actuator 42 for operating the mainvalving member 40 comprises a main actuator housing 86 which is securedby three screws 87 to the end cap 25. A diaphragm 88 sandwiched betweenthe main actuator housing 86 and the end cap 25 is secured to the mainspindle 41 by a pair of mounting discs 89 fast on the main spindle 41.The diaphragm 88 and the main actuator housing 86 form a vacuum cavity95. Main biasing means comprising a main compression spring 90 actingbetween the main actuator housing 86 and the mounting discs 89 urge themain spindle 41 downwardly, and in turn, the main valving member 40 intothe closed position. A vacuum is applied to the vacuum cavity 95 througha vacuum port 91 of the main actuator housing 86 for urging the mainspindle 41 upwardly and in turn the main valving member 40 into the openposition. An exhaust port 92 through a portion 93 of the end cap 25maintains the pressure on the side of the diaphragm 88 opposite thevacuum at atmospheric pressure. A bellows seal 94 tightly and sealablyengages the main spindle 41 and a portion 95 of the end cap 25 formingthe bore 84 for ensuring an airtight seal between the buffer chamber 24and the main actuator housing 86.

Turning now to the secondary valving member 50, the secondary valvingmember 50 is provided with a peripheral valve face 98 for sealablyengaging a valve seat 99 extending around the discharge outlet opening49. A secondary spindle 100 extends downwardly from the secondaryvalving member 50 and is slidably located in a carrier bore 102 formedin a carrier 103 centrally located in the discharge outlet opening 49,and which is carried on three mounting members 104 extending inwardlyfrom the periphery of the discharge outlet opening 49. First secondarybiasing means comprising a first compression spring 105 acting betweenthe carrier 103 and a flange 106 extending around the secondary spindle100 urges the secondary valving member 50 into a closed position (seeFIG. 4) with the valve face 98 sealably engaging the valve seat 99 forclosing the discharge outlet opening 49. An operating member 107 forurging the secondary valving member 50 into an open position (see FIG.3) with the valve face 98 disengaged from the valve seat 99 for openingthe discharge outlet opening 49 is centrally and slidably located in abore 108 in the base 14 of the lower housing 8. A bushing 109 in thebore 108 slidably engages the operating member 107. A secondaryactuating means, in this case, a vacuum operated secondary diaphragmactuator 110 operates the operating member 109. The secondary actuator110 comprises a secondary actuator housing 112 which is secured by threescrews 114 to the base 14 of the lower housing 8. A diaphragm 115 issandwiched between the secondary actuator housing 112 and a portion 116of the base 14 and is secured to the operating member 107 by a pair ofmounting discs 117 fast on the operating member 107. The diaphragm 115and the secondary actuator housing 112 form a vacuum cavity 113. Secondsecondary biasing means comprising a second compression spring 118acting between the secondary actuator housing 112 and one of themounting discs 117 urges the operating member 107 into engagement withthe secondary spindle 100 for in turn urging the secondary valvingmember 50 into the open position. A vacuum is applied to the vacuumcavity 113 through a vacuum port 119 in the secondary actuator housing112 for urging the operating member 107 out of engagement with thesecondary spindle 100 for permitting the secondary valving member 50 toclose under the action of the first spring 105. An exhaust port 120through the portion 116 of the base 14 maintains the side of thediaphragm 115 opposite the vacuum side of the diaphragm 115 atatmospheric pressure. A bellows seal 121 tightly and sealably engagesthe operating member 107 and a portion of the base 14 forming the bore108 for ensuring an airtight seal between the weighing chamber 15 andthe secondary actuator housing 112.

Activating means for activating and controlling the operation of themain valving member 40 and the secondary valving member 50 by applying avacuum to the respective main and secondary actuators 42 and 110comprises a pair of solenoid operated valves, namely, a main solenoidvalve 122 and a secondary solenoid valve 123, respectively. The main andsecondary solenoid valves 122 and 123 are mounted in the lowercompartment 79 of the secondary housing 53. The solenoid valves 122 and123 are mounted on a base plate 125 which is secured by screws, onescrew 126 of which is illustrated. A vacuum supply is supplied to inlets(not shown) of the valves 122 and 123 through an inlet vacuum line 130.Outlets 132 and 133 from the solenoid valves 122 and 123, respectively,are connected by pipes 127 and 128, respectively, to the vacuum ports 91and 119 of the main and secondary actuators 42 and 110, respectively,for operating the main spindle 41 and operating member 107,respectively. The control circuit 76 described below controls theoperation of the solenoid valves 122 and 123 in an operation sequencewhich is also described below.

Liquid sample storing means for storing a plurality of samples of milkcollected each time a weighed discrete quantity of milk is dischargedfrom the weighing container 45 comprises a milk sample reservoir 135 ofpartly annular shape extending around the bottom portion of the weighingchamber 15. The reservoir 135 is formed by an inner wall 136 whichextends upwardly from the base 14 of the lower housing 8 spaced apartfrom the side wall 10. Portions 137 of the inner wall 136 extendradially outwardly towards and engage the side wall 10 adjacent the mainoutlet pipe 36 for isolating the milk sample reservoir 135 from the mainoutlet pipe 36. As well as forming the milk sample reservoir 135, theinner wall 136 also forms a delivery chamber 138 into which weighed milkis discharged from the weighing container 45 for delivery through themain outlet pipe 36. Sampling means for drawing off a sample of milkeach time a weighed discrete quantity of milk is discharged from theweighing container 45 comprises a sampling tube 140 extending from theinner wall 136 into the delivery chamber 138. The sample tube 140communicates with the milk sample reservoir 135 at one end andterminates at the other end in an upwardly directed opening 141 forreceiving milk samples as the weighed quantity is discharged from theweighing container 45. Overflow means, namely, three overflow slots 143located in the inner wall 136 at 120° intervals extend downwardly intothe inner wall 136 to facilitate overflow of excessive quantities ofmilk samples collected in the milk sample reservoir 135 into thedelivery chamber 138. Agitating means for agitating and mixing the milksamples collected in the reservoir 135 comprises three arcuate agitatingpaddles 145, each of which are carried on a respective paddle carrier146. The paddle carriers 146 are mounted on and extend radiallyoutwardly from a carrier cap 147 at 120° intervals around the operatingmember 107. The carrier cap is secured on the operating member 107 overthe bellows seal 121. The agitator paddles 145 are of substantiallyequal length and are arranged so that the paddles extend consecutivelyaround the reservoir 135. The paddle carriers 146 are accommodated inthe overflow slots 143 and are movable upwardly and downwardly for inturn moving the agitator paddles 145 upwardly and downwardly on upwardand downward movement of the operating member 107 each time thesecondary valving member 50 is operated for agitating and mixing themilk samples in the reservoir 135. A plurality of holes 148 are providedthrough each agitator paddle 145 for enhancing the mixing and agitatingaction of the agitator paddles 145.

Receiving means for receiving a milk sample collecting vessel, namely, acollection jar 149 for collecting a milk sample from the milk samplereservoir 135 comprises a receiving spigot 150 formed on a valve housing151 of a three position outlet valve 149, which is mounted beneath thelower housing 8. The outlet valve 144 is provided with four ports; afirst port 153 which is connected to and engaged with a secondary outletmeans, namely, a secondary outlet 154 from the milk sample reservoir 135for delivering the milk sample to the outlet valve 144; a second port155 for connection to and engagement with a branch tube 156 extendingfrom the main outlet pipe 36. A third port 158 which terminates in thereceiving spigot 150 delivers the milk sample into the collection jar149. A fourth port 159 which also terminates in the receiving spigot 150draws a vacuum on the collection jar for urging the milk sample into thecollection jar 149. The valve housing 151 defines a hollow cylindricalvalving chamber 152 which communicates the ports 153, 155, 158 and 159.A three position valving member 157 is rotatably mounted in the valvingchamber 152.

The valving member 157 is manually movable between and into the threepositions by a knob 160 which is rigidly mounted on a shaft 161extending from the valving member 157. In a first position illustratedin FIG. 12, the valving member 157 communicates the first and thirdports 153 and 158, respectively, and the second and fourth ports 155 and159, respectively. In this first position, when a collection jar 149 issealably engaged on the receiving spigot 150, a vacuum is applied to thecollection jar 149 for drawing the milk sample from the milk samplereservoir 135 into the collection jar 149. In a second positionillustrated in FIG. 13, the valving member 157 communicates the firstport 153 and the second port 155 for drawing any remaining milk samplein the milk sample reservoir 135 into the main outlet pipe 36 after adesired quantity of the milk sample has been collected in the collectionjar 149. In the third position illustrated in FIG. 14, the valvingmember 157 closes the first and second ports 153 and 155. This would bethe normal position of the outlet valve 144 while the meter 1 isweighing the milk and collecting the samples.

The receiving spigot 150 is sized to correspond with the innerdimensions of the neck of the collection jar 149 so that the collectionjar 149 can be releasably and sealably engaged on the spigot 150 in anairtight manner. It will be appreciated that the receiving spigot 150will only receive collection jars with appropriately dimensioned necks.Needless to say, if desired, an adaptor may be provided for adapting thespigot 150 for receiving jars of different size necks.

A tubular member 170 of circular cross-section extends downwardly fromthe base 22 of the upper housing 9 into the weighing chamber 15 fordelivering milk from the communicating opening 39 into the weighingchamber 45. Three baffles 172 extend transversely across the tubularmember 170 for minimizing the effect of the milk falling under gravityinto the weighing container 45 on the load cell 46.

A second communicating means for communicating the buffer compartment 24with the weighing compartment 15 for maintaining a vacuum applied to themain outlet pipe 36 in the buffer compartment 24, for, in turn,maintaining vacuum continuity between the upstream portion 3 and thedownstream portion 4 of the pipeline 2 comprises a communicating pipe175 extending upwardly from the base 22 of the upper housing 9 into thebuffer chamber 24. The communicating pipe 175 extends to a positionadjacent the end cap 25 to avoid any danger of milk overflowing throughthe communicating pipe 175 from the buffer chamber 24 into the weighingchamber 15 during normal operation of the meter 1. The communicatingpipe 175 has a second function during flushing out of the meter with acleaning fluid as will be described below.

As can be seen in FIGS. 1, 2 and 7, the main inlet pipe 35 is inclinedand is arranged in the end cap 25 to direct the milk circumferentiallyand downwardly into the buffer chamber 24 to minimize frothing of themilk in the buffer chamber 24.

Referring now to FIG. 15, the control circuit 76 for controlling theoperation of the meter will now be described. The control circuitcomprises a printed circuit board 180 on which a microprocessor 181 forcontrolling the operation of the meter is mounted. A timer 182 is alsomounted on the printed circuit board 180 for timing part of theoperating sequence of the main and secondary valving members 40 and 50as will be described with reference to FIG. 16, and for timing theweighing means as will also be described below. A pair of drivers 184and 185 mounted on the printed circuit board 180 operate the solenoidvalves 122 and 123 respectively, under the control of the microprocessor181. An analog to digital converter 186 mounted on the printed circuitboard delivers signals from the strain gauges 74 of the load cell 46 tothe microprocessor 181. An input terminal 187 is provided on the printedcircuit board 180 for connection of an input device 188, for example, akeyboard or the like to enable a farmer to key in the identity of a cowbeing milked, which can subsequently be correlated in the microprocessor181 with the measured quantity of milk, and also for keying in othercommands to the microprocessor 181. An output terminal 189 is providedon the printed circuit board 180 for facilitating connection of anoutput device, for example, a visual display and printer unit 190 forenabling the recorded measured quantity of milk and the identity of thecow to be displayed and/or printed. Other suitable electronic componentswhich may be required and will be well known to those skilled in the artwill be also be provided on the printed circuit board 180.

A weighing cycle of the meter for weighing one discrete quantity of milkwill now be described.

Under vacuum from the downstream portion 4 of the pipeline 2, milk fromthe upstream portion 3 of the pipeline 2 is continuously fed into thebuffer chamber 24. With the secondary valving member 50 closing thedischarge outlet opening 49 of the weighing container 45, and the mainvalving member 40 open, milk in the buffer chamber 24 flows undergravity into the weighing container 45, in which a discrete quantity ofmilk collects. The microprocessor 181 under the control of suitablesoftware acts as a monitoring means and reads the load cell 46 while themilk is flowing into the weighing container 45. On the load cell 46recording a predetermined weight equivalent to a weight of approximately500 grammes of milk in the weighing container 45, the main valvingmember 40 is immediately closed by operating the solenoid valve 122 toapply a vacuum on the vacuum port 91 of the main diaphragm actuator 42.The secondary valving member 50 is retained closed, and themicroprocessor immediately activates the timer 182 to time apredetermined settling time period of one second to enable the discretequantity of milk in the weighing container 45 and the weighing container45 to settle, see FIG. 16. After the timer has timed the settling timeperiod, the microprocessor 181 again reads the load cell and records theweight read from the load cell 46 which is the settled weight of thediscrete quantity of milk allowing for the weight of the weighingcontainer 45. The read recorded weight is stored. The weight read fromthe load cell 46 after the settling time period allowing for the weightof the weighing container 45 is a relatively accurate weight of thediscrete quantity of milk in the weighing container 45. On themicroprocessor 181 having read the settled weight from the load cell 46,the solenoid 123 is operated to release the vacuum on the vacuum port119 of the secondary actuator 110 for opening the secondary valvingmember 50, for in turn, discharging the weighed discrete quantity ofmilk from the weighing container 45 into the delivery chamber 138, andin turn, through the main outlet pipe 36 into the downstream portion 4of the pipeline 2. As the weighed discrete quantity of milk is beingdischarged through the discharge outlet opening 49, a sample of the milkis collected in the milk sample reservoir 135. Simultaneously withoperating the secondary actuator 110 for opening the secondary valvingmember 50 the microprocessor operates the timer 182 for timing apredetermined discharge time period of two seconds during which thesecondary valving member 50 is retained in the open position for thedischarge of the weighed discrete quantity of milk from the weighingcontainer 45 under gravity, see FIG. 16. On the timer 182 having timedthe discharge time period, the solenoid 123 is operated by themicroprocessor 181 for in turn operating the secondary actuator 110 forclosing the secondary valving member 50. The timer 182 times a furthertime period, namely, a predetermined delay time period of half a secondafter which the microprocessor 181 operates the solenoid valve 122 foroperating the main actuator 42 for opening the main valving member 40,see FIG. 16. The next discrete quantity of milk flows under gravity fromthe buffer chamber 24 into the weighing container 45 and the nextweighing cycle commences. At the end of each weighing cycle, therecorded settled weights of the discrete quantities of milk read by themicroprocessor 181 are cumulatively stored in a suitable weight storingmeans in the microprocessor 181 so that on milking of a cow having beencompleted, the total weight of milk milked from the cow can be displayedand/or printed and recorded against the identity of the animal. Thetotal weight of milk is the summation of the settled weights of thediscrete quantities of milk.

During operation of the meter 1, while the meter 1 is sequentiallyweighing the discrete quantities of milk, the outlet valve 144 is in thethird position and isolates the secondary outlet 154 and the main outletpipe 36 from the receiving spigot 150. In other words, the valvingmember 157 of the outlet valve 144 is in the third position illustratedin FIG. 14.

When the cow has been milked, and it is desired to collect a sample ofthe milk samples in the milk sample reservoir 135, a collection jar 149is engaged on the receiving spigot 150. The valving member 157 is urgedby the knob 160 into the first position illustrated in FIG. 12 wherebythe first and third ports 153 and 158 and second and fourth ports 155and 159 communicate for drawing the milk sample into the collection jar149. When a desired quantity of milk sample has been collected in thecollection jar 149, the valving member 157 is urged by the knob 160 intothe second position (FIG. 13) whereby the secondary outlet 154 isconnected to the main outlet pipe 36 for drawing the remaining milksample in the milk sample reservoir 135 into the main outlet pipe 36. Onthe milk sample reservoir 135 having been emptied, the valving member157 is urged into the third position (FIG. 14) by the knob 160.

After the last of the quantities of milk which have been milked from acow has been weighed and cumulatively stored in the microprocessor 181,the cumulative weight of milk cross-referenced with the identity of thecow is saved in the microprocessor 181 for further use. Appropriatecommands are then inputted into the microprocessor 181 through thekeyboard 188 for resetting the microprocessor to commence weighing milkfrom the next cow. The identity of the cow is also keyed into themicroprocessor 181 through the keyboard 188 for subsequentcross-referencing and saving with the weight of the milk.

The microprocessor 181 is also programmed to operate the meter 1 duringa washing and flushing cycle. In other words, the meter 1 is operated insuch a way that all parts of the meter 1 which come into contact withmilk can be flushed out during washing and flushing out of the milkline. The operation of the meter 1 during a washing cycle will now bedescribed. The main valving member 40 and the secondary valving member50 are both closed. Flushing liquid being flushed through the pipeline 2is delivered into the buffer chamber 24 through the main inlet pipe 35.The flushing liquid accumulates in the buffer chamber 24 until itreaches the level of the top of the communicating pipe 175 at whichstage the flushing liquid flows through the communicating pipe 175 intothe weighing container 45. The flushing liquid then accumulates in theweighing container 45 and overflows over the lip 51 of the weighingcontainer 45 into the milk sampling reservoir 35 in the weighing chamber15. The flushing liquid then overflows through the overflow slots 143 inthe inner wall 136, and in turn, through the delivery chamber 138 andthrough the main outlet pipe 36. The flushing liquid then flows throughthe downstream portion 4 of the pipeline 2. As can be seen in FIG. 3,the communicating pipe 175 is provided over the weighing container 45 sothat the flushing liquid flows directly into the weighing chamber 45.The lip 51 of the weighing container 45 is also positioned so that theflushing liquid overflowing from the weighing container 45 flows intoand collects in the milk sample reservoir 135. In general, the rate atwhich the flushing liquid is delivered through the meter 1 will be suchas to ensure that the weighing chamber 15 will be substantially filledwith flushing liquid for cleaning thereof.

After the flushing liquid has been passed through the meter 1 for anappropriate period of time to ensure thorough washing and flushing ofthe meter, the main valving member 40 and the secondary valving member50 are opened to facilitate flushing of the main and secondary valvingmembers 50 and 55 and the communicating openings 39 and the dischargeoutlet opening 49. The outlet valve 144 may also be operated during theflushing cycle to facilitate flushing of the outlet valve 144 and alsofor draining residual flushing liquid from the milk sample reservoir 135into the main outlet pipe 36. During a flushing cycle, a collection jar149 is provided on the receiving spigot 150. It is envisaged that incertain cases the main and secondary valving members may be alternatelyopened and closed after a predetermined time period or time periods tofacilitate alternate flushing of the buffer and washing chambers.

While a particular shape and construction of main housing has beendescribed, any other suitable shape and construction of main housing maybe provided. It will be appreciated that other suitable main andsecondary valve means may be provided, and needless to say, othersuitable first and second communicating means and discharge outlet meansmay be provided. Needless to say, any other suitable shape andconstruction of weighing container may be provided.

It will also be appreciated that other suitable agitating means may beprovided for agitating milk samples in the milk sample reservoir, andneedless to say, while it is preferable, it is not essential that anagitating means be provided. It is also envisaged in certain cases thatthe meter may be provided without sample means, and it will of course beappreciated that where sampling means is provided, other suitablesampling means may be used.

While in the embodiment of the invention described, each discretequantity of milk weighed in the weighing container is approximately 500grammes, it will of course be appreciated that other suitable sizes ofdiscrete quantities may be weighed. For example, in seasons where milktends to froth excessively, it is envisaged that the weight of eachdiscrete quantity will be reduced to approximately 300 grammes or evenless. Needless to say, the weighing container may be sized to weighdiscrete quantities of any desired weight. While the settling period hasbeen described as being one second, the settling period may be set to beany desired value. However, in general, it is believed preferable that asettling period in the range of one-half second to three seconds isdesirable. While the discharge time period has been described as beingtwo seconds, this will be a function of the size of each discretequantity of milk in the weighing container, and also of the size of thedischarge outlet. However, the discharge time period should besufficient to allow complete emptying of the weighing container aftereach discrete quantity of milk has been weighed. In general, it ispreferable that the discharge time period should not exceed three orfour seconds, otherwise, the weighing cycle time will be unduly slow. Incertain cases, it is envisaged that the main valve means may not beresponsive to the weighing means, rather, the main valve means would beresponsive to the timer for closing the main valve means after apredetermined time which would allow a discrete quantity of milk to bedelivered into the weighing means. However, such an arrangement wouldnot provide as efficient a meter as would be provided where the mainvalve means is responsive to the weighing means.

While the meter has been described as comprising a control circuit whichincludes a timer, the timer may be implemented in the microprocessor,and while the weight storing means has been described as being a storewithin the microprocessor, a separate random access memory may beprovided in the control circuit associated with the microprocessor forcumulatively storing the discrete quantities of milk.

While the meter has been described for measuring the quantity by weightof milk flowing in a pipeline, it will be appreciated that the meter maybe used for measuring quantity by weight of any liquid flowing in apipeline or otherwise.

The capacity of the buffer chamber should be sufficient for accumulatingmilk flowing into the meter while a discrete quantity of milk is beingweighed. Additionally, the capacity of the buffer chamber and the heightof the communicating pipe should be such as to avoid the overflow ofmilk or milk froth from the buffer chamber into the weighing container45.

While the second communicating means has been described as being acommunicating pipe, any other suitable second communicating means may beprovided for communicating the vacuum between the weighing chamber andthe buffer chamber.

We claim:
 1. A meter for measuring the quantity by weight of a flowingliquid, the meter (1) comprising:a housing (7) defining a buffer chamber(24) for receiving and holding the liquid to be weighed, and a weighingchamber (15) within which the liquid is weighed, the weighing chamber(15) being located below the buffer chamber (24), a first communicatingmeans (39) for communicating the buffer chamber (24) and the weighingchamber (15) for accommodating liquid flow under gravity from the bufferchamber (24) to the weighing chamber (15), a main inlet means (35) beingprovided into the buffer chamber (24) for the liquid, a main outletmeans (36) being provided from the weighing chamber (15) for deliveringweighed liquid therefrom, a weighing means (45,46) for sequentiallyweighing discrete quantities of the liquid, the weighing means (45,46)being located in the weighing chamber (15) for receiving the liquid fromthe first communicating means (39), a discharge outlet means (49) fromthe weighing means (45,46) for delivering the weighed discretequantities of the liquid from the weighing means (45,46) into theweighing chamber (15), a main valve means (40) co-operating with thefirst communicating means (39) for selectively closing the firstcommunicating means (39) for isolating the weighing chamber (15) fromthe buffer chamber (24) after each discrete quantity of liquid has beendelivered into the weighing means (45,46), a secondary valve means (50)co-operating with the discharge outlet means (49) for closing thedischarge outlet means (49) and for selectively opening the dischargeoutlet means (49) after each discrete quantity of the liquid has beenweighed in the weighing means (45,46), a sampling means (140) forcollecting samples of the liquid, the sampling means (140) being locatedin the weighing chamber (15) beneath the discharge outlet means (49) ofthe weighing means (45,46) for collecting a liquid sample from theliquid being discharged from the weighing means (45,46) each time aweighed discrete quantity of the liquid is discharged from the weighingmeans (45,46), and a liquid sample storing means (135) communicatingwith the sampling means (140) for storing the liquid samples receivedfrom the sampling means (140).
 2. A meter as claimed in claim 1characterized in that the main valve means (40) is responsive to theweighing means (45,46) for closing the first communicating means (39) onthe weighing means (45,46) determining that the approximate weight ofthe liquid in the weighing means (45,46) is equal to a predeterminedweight, and the secondary valve means (50) is responsive to the weighingmeans (45,46) for opening the discharge outlet means (49) on theweighing means (45,46) having determined a substantially steady stateweight of each discrete quantity of liquid in the weighing means(45,46).
 3. A meter as claimed in claim 1 characterized in that the mainvalve means (40) is responsive to the secondary valve means (50) foropening the first communicating means (39) on the secondary valve means(50) having closed the discharge outlet means (49).
 4. A meter asclaimed in claim 1 characterized in that the meter (1) comprises atiming means (182).
 5. A meter as claimed in claim 4 characterized inthat the secondary valve means (50) is responsive to the timing means(182) for closing the discharge outlet means (49) on the timing means(182) having timed a predetermined discharge time period after thesecondary valve means (50) has opened the discharge outlet means (49),and the main valve means (40) is responsive to the timing means (182)for opening the first communicating means (39) on the timing means (182)having timed a predetermined delay time period after the secondary valvemeans (50) has closed the discharge outlet means (49).
 6. A meter asclaimed in claim 4 characterized in that the weighing means (45,46) isresponsive to the timing means (182) for determining the steady stateweight of each discrete quantity of liquid in the weighing means (45,46)on the timing means (182) having timed a predetermined settling timeperiod after the weighing means (45,46) has determined the approximateweight of liquid in the weighing means (45,46) being equal to thepredetermined weight.
 7. A meter as claimed in claim 1 characterised inthat the weighing means (45,46) comprises a weighing container (45)defining a hollow interior region (43) for receiving the liquid throughan open mouth (44), and for holding the liquid during weighing, theweighing container (45) being mounted on the housing (7) by a load cell(46) for weighing the liquid.
 8. A meter as claimed in claim 7characterized in that the load cell (46) comprises a shear beam loadcell (46) which is mounted horizontally and externally of the housing(7), and a substantially horizontal carrier shaft (58) extends centrallyfrom the load cell (46) through a side wall (47) of the housing (7) andis sealably engaged therein for carrying the weighing container (45). 9.A meter as claimed in claim 1 characterized in that the main valve means(40) comprises a main valving member (40) co-operating with the firstcommunicating means (39) and being movable between an open position withthe buffer chamber (24) and the weighing means (45,46) communicating anda closed position isolating the buffer chamber (24) from the weighingmeans (45,46), and a main actuating means (42) is provided for movingthe main valving member (40) between the closed position and the openposition, and the main actuating means (42) comprising a vacuum operatedmain diaphragm actuator (86,88), the main diaphragm actuator (86,88)being arranged for urging the main valving member (40) into the openposition under vacuum, and a main biasing means (90) is provided forurging the main valving member (40) into the closed position.
 10. Ameter as claimed in claim 1 characterized in that the secondary valvemeans (50) comprises a secondary valving member (50) co-operating withthe discharge outlet means (49), the secondary valving member (50) beingmovable between an open position with the discharge outlet means (49)open to a closed position with the discharge outlet means (49) closed,and a secondary actuating means (110) is provided for moving thesecondary valving member (50) between the open and closed positions, andan operating member (107) operably connects the secondary actuatingmeans (110) with the secondary valving member (50), the operating member(107) being disengagable with the secondary valving member (50) on thesecondary valving member (50) being in the closed position, thesecondary actuating means (110) comprising a vacuum operated secondarydiaphragm actuator (112,115), the vacuum operated secondary diaphragmactuator (112,115) being arranged for operating the secondary valvingmember (50) into the closed position on a vacuum being applied, and afirst secondary biasing means (105) is provided for urging the secondaryvalving member (50) into the closed position, and a second secondarybiasing means (118) is provided for urging the secondary valving member(50) into the open position, and a baffle means (172) is provided in thefirst communicating means (39) for minimizing the effect of the liquidflowing into the weighing means (45,46) on the weighing means (45,46).11. A meter as claimed in claim 1 characterized in that a control means(76) is provided for controlling the operation of the meter (1), thecontrol means (76) comprising a monitoring means (181) for reading theoutput of the weighing means (45,46), a weight storing means (181) forcumulatively storing the steady state weight of the discrete quantitiesof liquid read by the monitoring means (181), the control means (76)also comprising the timing means (182), and the activating means(122,123) for activating the operation of the main and secondary valvemeans (40,50), the activating means (122,123) comprising respective mainand secondary solenoid valves (122,123) for applying a vacuum to therespective main and secondary actuating means (42,110).
 12. A meter asclaimed in claim 1 characterized in that a second communicating means(175) is provided for communicating the buffer chamber (24) with theweighing means (45,46) for maintaining the buffer chamber (24) andweighing means (45,46) at substantially the same pressure, the secondcommunicating means (175) being located to avoid flow of liquid throughthe second communicating means (175) from the buffer chamber (24) to theweighing means (45,46) during normal operation of the meter (1).
 13. Ameter as claimed in claim 1 characterized in that the meter (1) isadapted for connecting into a pipeline (2) in which the liquid isflowing so that all the liquid flowing in the pipeline (2) flows throughthe meter (1), the main inlet means (35) being adapted for connecting toan upstream portion (3) of the pipeline (2), and the main outlet means(36) being adapted for connecting into a downstream portion (4) of thepipeline (2), the main housing (7) being airtight for maintaining avacuum applied to the pipeline (2) and for maintaining the said vacuumin the housing (7).
 14. A meter as claimed in claim 1 characterized inthat the meter (1) is suitable for connecting into a milk pipeline (2)delivering milk from a milking cluster to a milk holding vacuum jar, themeter (1) being suitable for measuring the quantity of milk by weightflowing in the pipeline (2).
 15. A meter as claimed in claim 1characterized in that the liquid sample storing means (135) is locatedin the weighing chamber.
 16. A meter as claimed in claim 1 characterizedin that an overflow means (143) is provided from the liquid samplestoring means (135) for delivering an overflow of liquid samples to themain outlet means (36).
 17. A meter as claimed in claim 1 characterizedin that an agitating means (145) is provided for agitating the liquidsamples in the liquid sample storing means (135), the agitating means(145) being operable on movement of the secondary valve means (50). 18.A meter as claimed in claim 1 characterized in that a receiving means(150) for releasably receiving a collecting vessel (109) for collectingliquid samples is provided, the receiving means (150) communicating withthe liquid sample storing means (135) through a secondary outlet means(154) from the liquid sample storing means (135).
 19. A meter as claimedin claim 18 characterized in that an outlet valve means (144) isdisposed between the secondary outlet means (154) and the receivingmeans (150) for selectively communicating the receiving means (150) withthe secondary outlet means (154) for delivering liquid samples from theliquid sample storing means (135) to a collecting vessel (149) locatedon the receiving means (150).
 20. A meter as claimed in claim 19characterized in that the outlet valve means (144) selectivelycommunicates the liquid sample storing means (135) with the main outletmeans (36) for discharging liquid samples from the liquid sample storingmeans (135) to the main outlet means (36).
 21. A meter as claimed inclaim 19 characterized in that the outlet valve means (144) is a threeposition valve means (144) having a first position in which thereceiving means (150) is connected to the secondary outlet means (154)and the main outlet means (36) for applying a vacuum on the receivingmeans (150) for drawing liquid samples from the liquid sample storingmeans (135) into a collecting vessel (149) mounted on the receivingmeans (150), a second position in which the secondary outlet means (154)is connected to the main outlet means (36) for drawing liquid samplesinto the main outlet means (36), and a third position in which thesecondary outlet means (154) and the main outlet means (36) arerespectfully closed and isolated from the receiving means (150) and fromeach other.
 22. A method for measuring the quantity by weight of aflowing liquid, the method comprising the steps offeeding the liquidthrough a main inlet means (35) into a buffer chamber (24) formed in ahousing (7) which also forms a weighing chamber (15) which is locatedbeneath the buffer chamber (24), sequentially delivering discretequantities of the liquid from the buffer chamber (24) under gravitythrough a first communicating means (39) into a weighing means (45,46)which is located in the weighing chamber (15) by opening a main valvemeans (40) located in the first communicating means (39), isolating theweighing means (45,46) from the buffer chamber (24) after each discretequantity of liquid has been delivered into the weighing means (45,46) byclosing the main valve means (40), sequentially determining the weightof the discrete quantities of liquid in the weighing means (45,46),discharging the weighed discrete quantities of liquid from the weighingmeans (45,46) into the weighing chamber (15) through a discharge outletmeans (49) from the weighing means (45,46) by opening a secondary valvemeans (50) which cooperates with the discharge outlet means (49) forclosing the discharge outlet means (49) during weighing of each discretequantity of the liquid for subsequent delivery of the weighed liquidthrough a main outlet means (36) from the weighing chamber (15), takinga liquid sample of each weighed discrete quantity of liquid as thediscrete quantity of liquid is being discharged from the weighing means(45,46) by a sampling means (140) located beneath the discharge outletmeans (49) from the weighing means (45,46), and storing the liquidsamples in a liquid sample storing means (135) which communicates withthe sampling means (140) for subsequent collection.
 23. A method asclaimed in claim 22 characterized in that the weighing means (45,46) isisolated from the buffer chamber (24) on the weighing means (45,46)having determined that the approximate weight of liquid in the weighingmeans (45,46) is equal to a predetermined weight, and the weighing means(45,46) determines a substantially steady state weight of each discretequantity of liquid.